Fire alarm systems typically include one or more centralized fire alarm panels for controlling and/or receiving information from sensors and notification devices distributed throughout a structure. Such fire alarm panels, sensors, and notification devices are typically connected to one another by conductive field wiring that can extend many hundreds, or even thousands, of feet. Due to its length, the field wiring is susceptible to transient electrical energy that may be generated by sources such as nearby lightning strikes and electrical motor startups. Such transient energy strikes can damage or disable a fire alarm system, causing premature failure and rendering the system incapable of detecting and/or providing notification of hazardous conditions. Fire alarm systems are therefore required to pass certain tests to demonstrate that electrical protection circuitry within such systems can resist various levels of transient energy. For example, Underwriters Laboratories (UL) 864, which sets forth accepted standards for control units and accessories for fire alarm systems, prescribes a test wherein fire alarm system circuitry is exposed to a plurality of electrical energy pulses across a range of voltages. These energy pulses place stress on the protection circuitry within a fire alarm system and thereby identify deficiencies in such circuitry.
While stress tests such as the one described above are generally effective for evaluating the performance of fire alarm system protection circuitry at the particular time such a test is performed, there have heretofore been no means for continuously monitoring fire alarm systems for the occurrence of actual transient energy events. Knowledge of the number and severity of such events could be useful for determining whether an alarm system or its components should be preemptively repaired or replaced (i.e., prior to impending failure), or for determining the cause of an alarm system's failure after such failure has already occurred. For example, if an alarm system fails prior to the expiration of its expected useful life, a customer may assume that the premature failure resulted from deficiencies in the quality of the protection circuitry in the system, when the failure was in-fact caused by an inordinate number of transient energy strikes to the system.